Is the jest of the questioner's father, that she "always gives to her sister and takes nothing from her," a will for her to spend on her sister and bear the responsibility of her expenses, especially since she is now working and her future husband prefers that she does not work?

Your father's directive for you to spend on your sister is advice, not an obligatory will. A father is not permitted to take from one child's money to give to another. You are not responsible for your sister's financial support, and you are not obligated to provide her with money or to take from your husband's money. However, helping her in a way that does not harm you is an act of righteousness, kindness, and maintaining kinship ties.